Brake



March 29, 1932. G GUNN 1,851,357

BRAKE Filed April 1'7, 1929 2 Sheets-Sheet l E. G. GUNN March 29, 1932.

BRAKE Filed April 17. 1929 2 SheetsSheet Patented Mar. 29,, 1932 G.GUNW, @F RACINE, WECONSIN, ASSEGNQB ME THE NASH MGTGRQ GOTEFANY, GE

KETOSHA, WISCONSIN, A GORFUEATION F HARD Application filed April 17,

This invention relates to improvements in brake construction for motorvehicles, and more particularly to internal brake shoes having servoaction.

The principal object of the invention is to provide an improved andsimplified means for adjusting the brakes.

' A further object is to provide an improved and simplified constructionwhereby the w brake shoes-may automatically position themselves properlyrelative to the brake drum when in operation.

@ther novel features of construction will appear from time to time asthe following description proceeds. In carrying out my invention, 1utilize certain novel features of construction heretofore broadlydisclosed in prior application bearing Serial No. 343,585 filed March 1,1929, wherein a two-shoe brake of the servo type is arranged foroperation in either direction of rotation of the wheel, but with animproved and simplified construction of parts, as will hereinafter morefully appear.

The invention may best be understood by reference to the accompanyingdrawings, in which Figure 1 is a face view of a brake constructed inaccordance with my invention, with parts broken away to show certaindetails of construction.

Figure 2 is a detail top plan view of the brake shown in Figure 1 withparts shown in section.

Figure 3 is a detail bottom plan view of the brake band andconnectinglinks.

Figure 4 is a fragmentary detail of the adjusting device with thebacking plate removed.

Figure 5 is a section taken on line 5 Figure 1.

Figure 6 is a view similar to Figure 5, but showing the pinion inunlocked position.

Figure 7 is a fragmentary view showing a modified form of connectionbetween the two brake shoes.

Referring now to details of the drawings, the general construction issimilar to that disclosed in my copending application. Serial No.343,585 and comprises a brake drum 1929. Serial No. 355,731.

10 carried b the wheel in the usual manner and the bac ng plate 12 ismounted on the wheel spindle (not shown) having the bra-king mechanismcarried thereon.

The braking mechanism shown herein comprises two shoes 20 and 21arranged in reversed position relative to each other and having slottedengagement with anchors 16 and 17 respectively so as to permit servoaction in either direction of rotation of the wheel, as will presentlyappear. An auxiliary pivotal connection is provided adjacent theanchored end of shoe 21 so as to permit the main part of the shoecarrying the brake lining 36 to position itself relative to the drumwhen the brake is applied. This pivotal connection is provided between alink 26 forming the anchored end of the shoe 21 and the shoe web 25 ofthe main portion of shoe 21. In the form shown, said shoe web has acircular portion 28 hinged in a recessed portion 28a of the link 26.

When the brake is in idle postion, a stop 29 on web 25 is held inengagement with the end surface 30 of the link 26. The brake is held incontracted or idle position by suitable means, such as a spring 31,connected from. an car 32 projecting inwardly from the hinged end oflink 26. The opposite end of spring 31 is connected to an ear 36?) onthe opposite shoe 20, as will hereinafter more fully be described.

()ne or more eccentric centering devices 18a may also be provided, ifdesired, to control the idle position of the shoe, as for instance, shoe21. as shown.

The shoes 20 and 21 are maintained-in contracted position against stops1818 carried by the backing plate and suitably disposed within theshoes.

Braking pressure is applied by an equalizer device indicated generallyat 40, disposed between the anchored ends of the shoes 20 and 21. Theequalizer device 40 is operated each provided with opposed curvedsurfaces 49-49 which normally engage each other on a line coincidentwith the axis of the operating shaft 46, as shown in Figure 1. Thearrangement is such that b rotation of the operating shaft 46, the equaizer links 4848 may be spread more in one direction than the other,depending upon the direction of rotatlon of the drum, but with saidequalizer links trans mitting substantially equal pressure on the endsof the brake shoes through the rolling action of the mutually engagedsurfaces 49-449, as described.

Referring now to features of construction which form the subject matterof this invention, it will be observed that the unanchored ends of shoesand 21 are pivotally connected by a link 41, herein comprising a pair ofplates 41a-41a on opposite sides of the shoe webs (see Figure 3). Theshoes are adjusted relative to the drum by a device preferably disposedadjacent the anchored end of shoe 20 to lengthen or shorten theeffective length of the latter. This adjusting device consist-3 of amember a which forms the anchored end of the shoe 20 and is providedwith a pair of spaced plates 350-350 which overlap opposite sides of theweb 35 of the main part of shoe 20. The plates 350-350 are slidablecircumferentially relative to said web 35 and are moved by means of apinion 37 mounted between plates 350350 and meshing with rack teeth 37 aformed on the web 35 adjacent its end. The parts are guided forcircumferential movement by suitable means,

such as pins 4242 carried by the web 35 and movable in slots 42a42aarranged circumferentially of the plates 35c350.

The pinion 37 is actuated by means of a shaft 43 having bearing supportin an ear 43a carried by member 35a at one side of the web 35, andhaving a squared end 435 fitting in said pinion. Said shaft is shiftablelongitudinally relative to the ear 43a and pinion 37. A collar 44 havinga series of gear teeth is carried on said shaft beneath the ear 43a, theentire shaft and collar being normally under tension of coil spring 44?;on the outer end of said shaft so as to force the teeth of collar 44into engagement with locking projections 440 carried on the inner sideof said ear (see Figure 6). The arrangement is such that the pinion 37and the rack teeth 38 are normally held in locked position, but may beunlocked by forcing the shaft 43 inwardly by means of a suitable tool,as for instance, a screw driver, which may be inserted through aperturein the backing plate (see Figure 5) and applied in slot 430 so as tomove the collar 44 out of locked position, as shown in Figure 6. Whenthus unlocked, the pinion 37 may be rotated to any desired position ofadjustment. Upon release of the pressure upon shaft 43, the collar 44will automatically reassume its locked postion by action of the spring445, as soon as the collar is rotated slightly to a position where itsteeth register with the locking projections 440.

In the modified form of joint shown in Figure 7, a connection betweenthe unanchored ends of shoes 20 and 21 is provided by means of arelatively loose fitting joint, including pivotal member 52 on shoe 20,which fits recess 53 on shoe 21, so as to permit the connected shoes .toshift radially a limited distance relative to each other, but said pivot52 is retained by a relatively light spring 54 which directly connectsadjacent parts of the joint and normally holds the part 52 in the upperpart of recess 53. This arrangement provides a normally fixed pivotalmovement of shoe 20 relative to shoe 21 but when the shoes are inbraking position, with the shoe 21 acting as the anchor for shoe 20, thelatter shoe may shift outwardly against the rela-.

tively light tension of spring 54 and thus automatically position itselfrelative to the drum.

Although I have shown and described the particular embodiment of myinvention, it will be understood that I do not wish to be limited to theexact construction shown and described, but that various changes andmodifications may be made without departing from the spirit and scope ofmy invention.

I claim as my invention:

1. In combination with a servo brake including a system of cooperatingshoes, anchor means and applying means therefor,

means for adjusting said shoes comprising acircumferentially-telescoping connection tween adjacent members of saidsystem, including rack and pinion actuating devices carried by saidmembers, and means for locking said pinion relative to one of saidmembers.

2. In combination with a servo brake including a drum, a backing plate,a system of cooperating shoes, anchor means and applying means therefor,means for adjusting said shoes comprising acircumferentially-telescoping connection between adjacent mem bers ofsaid system, includin rack and pinion actuating devices carried by saidmembelars and accessible through said backing p ate.

3. In a brake, a drum, two connected shoes anchored for servo action ineither direction of rotation of said drum, and adjusting means carriedby one of said shoes adjacent its anchored end comprising a telescopingconnection means for positively moving said connection in eitherdirection to effect the adjustment of both of said shoes and means forlocking said connection in any one of several adjusted positions.

4. In a brake, a drum, two connected shoes anchored for servo action ineither direction of rotation of said drum, and ad'usting means carriedby one of said shoes a jacent its anchored end comprising a telescopingconnection, rack and pinion actuating devices therefor, and means forlocking said connection in any one of several adjusting positions.

5. In combination with a servo brake including a drum, a backing plate,a system of (to-operating shoes, anchor means and applying meanstherefor, a circumferentially telem scoping connection between adjacentmembers of said system including a co-operating rack and pinion and aspring pressed actuating member for said pinion normally looking thelatter in fixed position but movable out of locking position to rotatesaid pinion in either direction.

6. In combination with a servo brake including a drum, a backing plate,a system of co-operating shoes, anchor means and applying meanstherefor, a circumferentially telescoping connection between adjacentmembers of said system including a co-operating rack and pinion, saidpinion being disposed on an axis intersecting said backing plate, a

spring pressed actuating member for said pinion accessible through saidbacking plate, said actuating member normally locking said pinion, butmovable out of looking position to rotate said pinion in eitherdirection.

Signed at Racine this 21st day of March EARL G. GUNN.

